USGS Streamgage 11162620
Pilarcitos C below Stone Dam near Hillsborough, CA
Pilarcitos C below Stone Dam near Hillsborough, CA is USGS streamgage 11162620 in California, monitoring river discharge in hydrologic subbasin 18050006. It sits on the Pilarcitos C, alongside 2 other gauges Rivermatics tracks on the same river. It drains a watershed of about 7 square miles. Discharge records at this site go back to 1997. Typical flow runs near 1.5 cfs in July and 2.2 cfs in April, with the higher of the two arriving in April. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.
View live conditions & forecast →
Gauge details
- State
- California
- Drainage area
- 7 sq mi
- Gauge elevation
- 459 ft
- Subbasin (HUC-8)
- 18050006
- Coordinates
- 37.52462, -122.39937
- USGS site number
- 11162620
- Records begin
- 1997-10-01 (29 years)
- Rivermatics forecast
- 14-day flow outlook
14-day flow forecast
Based on observations through for Pilarcitos C below Stone Dam near Hillsborough, CA. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.
| Date | Low p10 | Expected p50 | High p90 | Range |
|---|---|---|---|---|
| 2.1 | 2.3 | 2.5 | ||
| 2.1 | 2.3 | 2.6 | ||
| 1.9 | 2.3 | 2.6 | ||
| 1.9 | 2.2 | 2.6 | ||
| 1.9 | 2.2 | 2.6 | ||
| 1.8 | 2.2 | 2.6 | ||
| 1.8 | 2.2 | 2.6 | ||
| 1.8 | 2.2 | 2.6 | ||
| 1.7 | 2.2 | 2.6 | ||
| 1.7 | 2.2 | 2.7 | ||
| 1.7 | 2.2 | 2.8 | ||
| 1.5 | 2.1 | 2.6 | ||
| 1.5 | 2.1 | 2.6 | ||
| 1.5 | 2 | 2.6 |
All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 29 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 0.4 | 3.1 | 44.2 | |
| February | 0.7 | 3.5 | 39.8 | |
| March | 0.6 | 3.1 | 35.7 | |
| April | 0.4 | 2.2 | 14 | |
| May | 0.2 | 1.7 | 5.5 | |
| June | 0.2 | 1.6 | 2.8 | |
| July | 0.2 | 1.5 | 2.3 | |
| August | 0.1 | 1.3 | 2.2 | |
| September | 0.1 | 1.3 | 2.1 | |
| October | 0.1 | 1.4 | 2.5 | |
| November | 0.1 | 1.5 | 3.2 | |
| December | 0.2 | 2 | 17 |
All values in cubic feet per second (cfs).
Common questions
- When does Pilarcitos C below Stone Dam near Hillsborough, CA normally run highest?
- February, on the long-term record. The median daily flow that month is about 3.5 cfs, against 1.3 cfs in August, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Pilarcitos C below Stone Dam near Hillsborough, CA?
- It depends on the month. In January, half of days historically fall near 3.1 cfs, with the middle 80% of days between 0.4 and 44.2 cfs. The month-by-month table on this page gives the full range.
- How long has Pilarcitos C below Stone Dam near Hillsborough, CA been measured?
- Discharge records at USGS site 11162620 begin in 1997, about 29 years, covering roughly 9,130 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Is there a flow forecast for Pilarcitos C below Stone Dam near Hillsborough, CA?
- Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
- Where is Pilarcitos C below Stone Dam near Hillsborough, CA?
- The gauge sits at 37.52462, -122.39937, in California, in hydrologic subbasin 18050006, at an elevation of about 459 feet, draining roughly 7 square miles.
- Can I use Pilarcitos C below Stone Dam near Hillsborough, CA data for flood or safety decisions?
- No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.
Upstream and downstream on the Pilarcitos C
Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Pilarcitos C in full.
- Pilarcitos C below Spillway near Hillsborough, CA 4 sq mi
- Pilarcitos C Ab Stone Dam near Hillsborough, CA 6 sq mi
- Pilarcitos C below Stone Dam near Hillsborough, CA this page